This project will test specific chemical agents in a variety of combinations with X-rays. The interaction between agents will be examined in 4 ways: using both exponentially growing and plateau phase cells in tissue culture; using selected tumors and normal tissues of the mouse; using a model mouse tumor system, and EMT6 sarcoma, to investigate single and combined modality effects on proliferating (P) and non-proliferating (Q) clonogenic cells; and using the receptivity of the lung parenchyma of the mouse to the development of metastases from blood-borne tumor cells. The tissue culture program is intended primarily as a screen, but will also include studies of a fundamental nature on the interaction of different modalities relative to the repair of sublethal and potentially lethal damage. Testing in the tumor and normal tissue systems is intended ultimately to provide information about the therapeutic ratio of different combinations of modalities, i.e., the effect of treatment on malignant cells relevant to the effect on normal tissues. Studies on P and Q clonogenic cells will be comprised of autoradiographic analysis of colonies grown in vitro after tumors are labeled in vivo. The receptivity of the lung to "metastases" after the intravenous injection of tumor cells is intended to determine which, if any, modalities predispose the treated subject to pulmonary metastases.